Sheet catch tray for automatic sheet feeding apparatus

ABSTRACT

The present invention relates to a sheet catch tray for an automatic sheet feeding apparatus mounted to a feeder portion of a reproduction apparatus or a printing machine, said sheet catch tray holding a stack of photosensitive sheets or printing paper and feeding sheets one by one continuously in cooperation with said automatic sheet feeding apparatus.

United States Patent 1 Okamoto [451 Sept. 11,1973

1 1 SHEET CATCH TRAY FOR AUTOMATIC SHEET FEEDING APPARATUS [75] Inventor: Toyoo Diramoto, Tokyo,.1apan [73] Assignee: KabushikiKaisha Ricoh,Tokyo,

Japan [22] Filed: Sept. 17, 1970 [21] App]. No.: 73,083

[30] Foreign Application Priority Data Oct. 22, 1969 Japan 44/84546 [52] US. Cl 271/61, 221/198, 271/39 [51] Int. Cl B65h H04 [58] Field 01 Search 271/39, 36, 61, 62;

[56] References Cited UNITED STATES PATENTS 1,582,610 4/1926 Johnson 271/39 3,343,716 9/1967 Peebles 221/52 X 3,339,916 9/1967 Tregay 271/36 2,922,644 1/1960 Perzentka 271/39 3,533,617 10/1970 Collins 271/39 3,635,468 H1972 Suzuki 271/61 Primary Examiner--Evon C. Bllll'llk Assistant Examiner-Bruce H. Stoner, Jr. Attorney-Craig, Antonelli, Stewart and Hill [57] ABSTRACT The present invention relates to a. sheet catch tray for an automatic sheet feeding apparatus mounted to a feeder portion of a reproduction apparatus or a printing machine, said sheet catch tray holding a stack of photosensitive sheets or printing paper and feeding sheets one by one continuously in cooperation with said automatic sheet feeding apparatus.

2 Claims, 5 Drawing Figures PATENTED E 1 I975 3.758.105

SHEET 1 BF 2 INVENTOR TOYOO O KR MOT'O BY HUB-mm,

5W k HLQQ.

ATTORNEYS PAIEMED EH 1 1m 3.758.105

SHEET 2 (IF 2 NUMBER OF COPIES INVENTOR Yoo OKRMOTO BYWQ ATTORNEYS SHEET CATCH TRAY FOR AUTOMATIC SHEET FEEDING APPARATUS The invention relates to a sheet catch tray for an automatic sheet feeding apparatus. This sheet catch tray for an automatic sheet feeding apparatus holds a supply of printing paper or cut photosensitive sheets in a reproduction apparatus or a printing machine for continuously feeding sheets in cooperation with an automatic paper-feeding apparatus mounted to the feeder portion of said reproduction apparatus.

For a better understanding of the invention, reference is made to the following detailed disclosure of this invention taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a perspective view ofa sheet catch tray for an automatic sheet feeding apparatus, illustrating one embodiment of the present invention;

FIGS. 2 and 3 are longitudinal sectional views of sheet catch trays, illustrating operative features thereof;

FIG. 4 is a view similar to those of FIGS. 2 and 3 but illustrating another embodiemtn of the present invention; and

FIG. 5 is a diagram showing a relation between the pressure of sheet separation fingers against a supply of sheets and the number of the sheets.

Referring to FIG. 1, it will be understood that the present sheet catch tray comprises a housing 1 for holding a supply of sheets, sheet separation fingers 2a and 2b for depressing both front corners of said sheets held in said housing 1, a sheet receiving plate 3 which is dropped down to the bottom of the housing 1 under gravitation and openings 4a and 4b formed in the front portion of said bottom of the housing 1. This sheet catch tray, as shown in FIG. 2, holds a stack of sheets 5 on the sheet receiving plate 3, and causes to fit loosely into the openings 4a and 412, two supporting posts 5 (only one of them being shown in the drawings) which are set in parallel with each other to the feeder portion of the reproduction apparatus, whereby the front portion of the sheet receiving plate 3 is supported. This sheet catch tray is mounted to the feeder portion of the reproduction apparatus in such a way as the back portion of the bottom of the housing 1 is supported by a housing supporting member 7 provided at the free end portion of an arm member 6 fixed to said feeder portion at the other end portion thereof, and the front portion of the housing 1 is suspended by the sheet separation fingers 2a and 2b. When the sheet catch tray is mounted to the feeder portion as mentioned above, a feed roller 8 provided at the feeder portion is pressed against said stack of sheets S by its own weight and the stack of sheets S is then depressed by the sheet separation fingers 2a and 2b at their front corners. In the sheet feeding operation, said roller 8 rotates in the direction shown by an arrow a, which causes the topmost sheet of the sheet stack S to proceed forward through frictional contact therewith. Since the front comers of the topmost sheet is depressed by the sheet separation fingers 2a and 2b, said topmost sheet thus driven forward will be raised to form an upwardly curved surface be tween said fingers 2a and 2b and the roller 8 until the topmost sheet becomes free from the separation fingers 2a and 2b, whereby said topmost sheet is fed forward, that is, in the direction shown by and arrow b. In this case, the drive of the topmost sheet depends greatly on p 2 the pressure of the separation fingers 2a and 217 against the stack of sheets S, and in order to insure the separation of the topmost sheet only from the stack, said pres sure must be adjusted properly. As to the preferable pressure, there is a certain allowable range which is determined by experiments.

The restraining pressure of the separation fingers 2a and 2b to the stack of sheets S (hereinafter being called finger pressure") depends mainly onthe weight of the housing 1 per se and the stack of sheets S contained therein. In the sheet catch tray, as the rear end of the sheet receiving plate 3 is in contact with the bottom of the housing 1, said finger pressure P is expressed by the following equation:

wherein L is the length from the front end of the housing 1 to the contact portion between the housing I and the housing support member 7; W, is the weight of the housing 1 at that portion; W is the weight of the housing 1 at the portion from the contact portion to the rear end; L, and L are respectively lengths from the contact portion to the points of action of W, and W that is, to the centers of the gravity of the above-mentioned portions; W, is the weight of the sheet receiving plate 3 and the stack of sheets S which bears on the contact portion between the rear end of the sheet receiving plate 3 and the housing I; and I0 is the length from this contact portion to the contact portion between said housing 1 and the housing receiving member 7.

In the equation (1), W, and W are mainly determined by the size of the housing 1 and the kind of its material, whereas L, L,, L and 10 are determined by the size of the housing 1 and the position of the contact portion between the housing 1 and. the housing support member 7. The size of the housing 1 is mainly determined by the size of a stack of sheets S to be housed therein, and W, is mainly determined by the quantity of the sheets. Generally speaking, among the abovementioned quantities, it is only W, that changes its value in the same sheet catch tray, and the value of W is decreased along with the successive feed of the sheets. Further, the equation (1) teaches that P is increased along with the gradual decrease of W,.

When the allowable limits of the finger pressure P is in the range from P,, to P, in FIG. 5 (this range being determined by experience as mentioned above), and the size of the housing 1 is such as to contain a certain size of sheets, and assuming that the quantities such as W,, W L, L,, L and 10 in the equation (1) are set in accordance with the position of the contact portion between the housing 1 and the housing supporting member 7 so that the finger pressure P may be within the range from P,, to P,, the finger pressure P will be increased along the straight line A in accordance with the successive decrease of the stack of sheets in the housing, for example, from the maximum number of sheets 200, that is, in accordance with the decrease of W, as seen in FIG. 5. In this case, however, due to the predetermined setting as mentioned above, the finger pres sure P will not be decreased to less than the lower threshold pressure P,, even if a large number of sheets are introduced, nor increased more than the upper threshold pressure P, even if the housing 1 becomes empty.

The above-mentioned art, however, has many drawbacks as described hereunder. When the contact portion between the housing 1 and the housing supporting member 7 is positioned as mentioned above, mounting such a sheet catch tray as contains sheets of certain larger sizes to a reproduction apparatus, the values of L and lo among the quantities in the equation (I) become larger, and therefore, the value of the instant finger pressure P is small from the beginning and becomes smaller than the lower threshold pressure P, when the number of sheets is large and the sheet feeding is not effected smoothly.

On the contrary, when such a sheet catch tray as contains sheets of certain smaller sizes is mounted, it will induce reversed undesirable phenomena. That is, as the values of L and 10 are small in this case, the value of the finger pressure P becomes large from the beginning, and its change is seen in a broken line B positioned above the full line A in FIG. 5, and therefore, the finger pressure P becomes greater than the upper threshold pressure P during the decreasing process of the stack of sheets, which does not insure smooth sheet feeding.

The instant problem lies in the position of the contact portion between the housing 1 and the housing support member 7, which determines the values of L, L L and lo in the equation (1 Both the arm member 6 and the housing support member 7 are fixed and their lengths are usually determined in accordance with a catch tray which contains a stack of sheets of the smallest size. For this reason, it is practically impossible to greatly change the position of the contact portion in accordance with the catch tray of all sizes. Further, assuming that the adjustment is effected whenever the size of the sheet is changed, the operation processes in a printing machine or a reproduction apparatus will be increased and complexity will also be increased.

It is, therefore, an object of the invention to provide a sheet catch tray for an automatic sheet feeding apparatus which overcomes the above-mentioned drawbacks and enables feeding of sheets of all sizes continuously and smoothly through the simplest way.

The invention will be hereinafter described with reference to an embodiment thereof illustrated in the accompanying drawings. In the following description, the reference numbers denoted in FIG. 1 to FIG. will be used as they are in order to avoid troubles of repeating the same explanation.

Referring to FIG. 1, the bottom plate of the housing 1 is provided with a protrusion 9 of any height which supports the rear portion of the sheet receiving plate 3. When such a sheet catch tray, as seen in FIG. 2, is mounted to a reproduction apparatus or a printing machine, the weights W, of both the stack of sheets S and the rear portion of the sheet receiving plate 3 bear on said protrusion 9.

Further, as seen in FIG. 2, the back portion of the bottom of the housing 1 isprovided with a fulcrum member 10 at the position corresponding to the housing supporting member 7, and in the present invention the fulcrum member 10 is in contact with the housing support member 7. The finger pressure P is expressed by the following equation:

P z (L /L) W (Lg/L) W -(l /L) W,

wherein I is the distance between the protrusion 9 and the fulcrum member 10.

The position of the protrusion 9 is changed as a design matter whenever the size of the housing I is changed in accordance with the size of a stack of sheets contained therein, and is determined so that the value of 1 in the equation (2) may be such as the finger pressure P is always within the allowable limiting range from P to P,. That is to say, in the sheet catch tray of the present invention, even if the stack of sheets S contained in the housing I is of any size, the finger pressure P may be changed to a suitable value along a straight line A as shown in FIG. 5 by means of the protrusion 9, and therefore, it is always possible to set the pressure within a preferable pressure range, which results in feeding a single sheet out of the stack of sheets S smoothly.

In FIG. 2, there are a large number of sheets in the sheet catch tray, while in FIG. 3 there are a less number of sheets in the same sheet catch tray. Even if the value of W, in the equation (2) is changed by the change of the number of the sheets, the finger pressure P will not be out of the range from P to P In case the fulcrum member 10 is set in such a position as the finger pressure P may become a suitable value in a sheet catch tray of a certain size, in a sheet catch tray of a smaller size the protrusion 9 is provided in such a position so that I in the equation (2) becomes smaller than L, while in a sheet catch tray of a larger size the protrusion 9 is provided in such a position that 1, becomes larger than L in the equation (2).

It is not always necessary to provide the fulcrum member 10, but it is desirable to provide it since it is by means of this fulcrum member 10 that the position of the sheet catch tray is changeable in design in accordance with the size of the sheet catch tray and since it is possible to set the values of L, L and L in the equation (2) so that the finger pressure P may be in the suitable range. Furthermore, in the case fulcrum member 10 is provided, the following advantages are obtainable. When there are plurality of sheets S in the housing 1, by adjusting the height of the fulcrum member 10, it is possible to design the fulcrum member 10 to contact the housing support member 7, and on the contrary, when the number of sheets S in the housing 1 decreases by feeding the sheets, it is possible to design so that the bottom surface of the housing 1 which rotates in the counterclockwise direction as seen in FIG. 2 to directly contacts a shoulder portion 7a of the housing support member 7 in accordance with the decrease of the sheets S. In this case, the position of the fulcrum is transferred to the front portion of the housing 1 during the sheet decreasing process and the values of L and L in the equation (2) become smaller while those of L and I become larger, and therefore, it is possible to decrease the finger pressure P which is increased gradually by the decrease of the height of the stack of sheets S somewhat.

In FIG. 4, there is shown a sheet catch tray which is provided with a protrusion 11 in place of the abovementioned protrusion 9, both the position and the height of said protrusion 11 being determined, that is, the position is determined so that, when the housing 1 is filled with a stack of sheets, the value of I in the equation (2) may be such as the finger pressure P becomes a suitable one, and the height thereof is determined so that, when the housing 1 is rotated on the protrusion 11 as a fulcrum in the counterclockwise direction to increase its inclination, the bottom surface of the sheet receiving plate 3 may become free from the protrusion 11 and at the same time the rear end 3a of the sheet receiving plate 3 may come in contact with the bottom of the housing 1. The condition in which said rear end 3a is supported by the housing 1 is shown in FIG. 4. By providing the protrusion 11 with the position and the height of which are set as mentioned above, the supporting position in the rear portion of the housing 1 which supports the sheet receiving plate 3 is transferred from the protrusion 11 to the rear end portion of the receiving plate 3 during the decreasing process of the stack of sheets S. Accordingly, the finger pressure P is changed in accordance with the equation (2) from the beginning of the sheet feeding operation to the middle of the operation, whereas the same is changed in accordance with the equation (I) from the middle of the operation. Comparing 1 in the equation (2) with lo in the equation (1), it is apparent that I is less than lo, the finger pressure P decreases suddenly during the decreasing process of the stack of sheets S, and therefore, it is seen that such a change may be shown by the broken line C in FIG. 5. According to the sheet catch tray of the present invention, in case the size of the stack of sheets S is extremely large and therefore the change of W, is extremely large, when W, is decreased, the finger pressure P becomes larger than the upper threshold pressure P (this is shown in a broken line C, in FIG. 5). In this case it is possible to maintain the pressure P in a suitable constant value by self adjusting the finger pressure P during the operating process.

Through each of theprotrusions 9 and 11 and the fulcrum member 10 is made in the shape of a flat narrow plate in the embodiments described above and illustrated in the drawings, in the sheet catch tray of the present invention their shapes may be optional, for example, they may be outwardly curved ones or flat wide plates. The protrusions 9 and 11 may be provided in the sheet receiving plate 3, not in the housing 1. Further, the mounting of the separation fingers 2a and 2b is of course optional, for example, they may be formed integral with the housing 1 as seen in FIG. 1 or they may be made as separate members and may be suitably fixed to the housing 1. The above-mentioned housing 1 is covered with a sheet protecting cover. This cover is slidable on the housing 1, and the cover is designed so as to be half or fully opened so that in the sheet feeding operation the separation fingers 2a and 2b and the roller 8 are positioned into pressure contact with the stack of sheets 8.

What is claimed is:

l. A sheet catch tray for an automatic sheet feeding apparatus comprising a housing, sheet separation fingers which depress both front corners of the sheets contained in said tray, a sheet receiving plate which is loosely dropped down to the bottom of the housing, openings formed in the bottom of said housing through which supporting posts are upwardly inserted to support the forward portion of said sheet receiving plate and a protrusion formed between the bottom of said housing and said sheet receiving plate to support the back portion of said sheet receiving plate, said protrusion being located at such a position so that the pressure of said sheet separation fingers against the sheets becomes a suitable pressure so as to separate a single sheet from the stack of sheets when said sheet receiving plate and the back bottom surface of said housing are supported by said supporting posts and a housing support member, respectively, and the front portion of said housing is suspended by said sheet separation fingers, and

wherein the protrusion is positioned so that the rear portion of the sheet receiving plate contacts the bottom of the housing when said housing is oscillated upon a fulcrum of the contact portion between the housing and the housing support member, and the point of gravity action of said sheets is transferred from said protrusion to the back portion of said housing when said sheet separation fingers are lowered in accordance with the decrease of the height of the stack of sheets, whereby the pressure of said sheet separation fingers is ma ntained at a suitable pressure so as to separate a single sheet from the stack of sheets. 2. A sheet catch tray for an automatic feeding apparatus comprising:

a housing having openings formed in the bottom thereof; sheet separation finger means mounted on said housing for depressing both front comers of sheets disposed in said tray and for supporting the front portion of said housing in its mounted position; a sheet receiving plate loosely supported on the bottom of said housing; supporting means, including a post member inserted through said openings in said housing for supporting the forward portion of said sheet receiving plate and a housing support member contacting the bottom of said housing at the outside thereof; and means for ensuring the application of a pressure of said sheet separation finger means against said sheets for separating a single sheet from a stack of sheets when said sheet receiving plate and said housing are supported by said supporting means and the front portion of said housing is suspended by said sheet separation finger means, comprising a protrusion member disposed between the bottom interior of said housing and said sheet receiving plate and being displaced with respect to the point of contact of said housing support member with said housing, wherein said protrusion member is positioned so that the rear portion of the sheet receiving plate contacts the bottom of the housing when said housing is rotated about a fulcrum of the contact point between the housing and said housing support member, and the point of gravity action of said sheets is transferred from said protrusion to the back portion of said housing when said sheet separation fingers are lowered in accordance with the decrease of the height of said sheets, whereby pressure of said sheet separation finger means is maintained so as to separate a single sheet from a plurality of sheets in a stack on said sheet receiving plate. 

1. A sheet catch tray for an automatic sheet feeding apparatus comprising a housing, sheet separation fingers which depress both front corners of the sheets contained in said tray, a sheet receiving plate which is loosely dropped down to the bottom of the housing, openings formed in the bottom of said housing through which supporting posts are upwardly inserted to support the forward portion of said sheet receiving plate and a protrusion formed between the bottom of said housing and said sheet receiving plate to support the back portion of said sheet receiving plate, said protrusion being located at such a position so that the pressure of said sheet separation fingers against the sheets becomes a suitable pressure so as to separate a single sheet from the stack of sheets when said sheet receiving plate and the back bottom surface of said housing are supported by said supporting posts and a housing support member, respectively, and the front portion of said housing is suspended by said sheet separation fingers, and wherein the protrusion is positioned so that the rear portion of the sheet receiving plate contacts the bottom of the housing when said housing is oscillated upon a fulcrum of the contact portion between the housing and the housing support member, and the point of gravity action of said sheets is transferred from said protrusion to the back portion of said housing when said sheet separation fingers are lowered in accordance with the decrease of the height of the stack of sheets, whereby the pressure of said sheet separation fingers is maintained at a suitable pressure so as to separate a single sheet from the stack of sheets.
 2. A sheet catch tray for an automatic feeding apparatus comprising: a housing having openings formed in the bottom thereof; sheet separation finger means mounted on said housing for depressing both front corners of sheets disposed in said tray and for supporting the front portion of said housing in its mounted position; a sheet receiving plate loosely supported on the bottom of said housing; supporting means, including a post member inserted through said openings in said housing for supporting the forward portion of said sheet receiving plate and a housing support member contacting the bottom of said housing at the outside thereof; and means for ensuring the application of a pressure of said sheet separation finger means against said sheets for separating a single sheet from a stack of sheets when said sheet receiving plate and said housing are supported by said supporting means and the front portion of said housing is suspended by said sheet separation finger means, comprising a protrusion member disposed between the bottom interior of said housing and said sheet receiving plate and being displaced with respect to the point of contact of said housing support member with said housing, wherein said protrusion member is positioned so that the rear portion of the sheet receiving plate contacts the bottom of the housing when said housing is rotated about a fulcrum of the contact point between the housing and said housing support member, and the point of gravity action of said sheets is transferred from said protrusion to the back portion of said housing when said sheet separation fingers are lowered in accordance with the decrease of the height of said sheets, whereby pressure of said sheet separation finger means is maintained so as to separate a single sheet from a plurality of sheets in a stack on said sheet receiving plate. 